Multiplexed trim valve system for an electrically variable hybrid transmission

ABSTRACT

A powertrain has an electrically variable hybrid transmission having an electro-hydraulic control system, plurality of electrical power units, and a plurality of torque transmitting mechanisms selectively engageable by the electro-hydraulic control system to provide four forward speed ranges, a neutral condition, an electric low speed mode, an electrically variable low and high speed mode, and two electrical power off drive home modes. The electro-hydraulic control system of the present invention has a multiplexed trim system for an electrically variable hybrid transmission. The multiplexed trim system allows engagement control of four torque transmitting mechanism and individual control of fluid flow to effect cooling of two motor/generators by multiplexing three trim valves with two logic valves.

TECHNICAL FIELD

The present invention relates to electro-hydraulic control systems forelectrically variable hybrid transmissions.

BACKGROUND OF THE INVENTION

Multi-speed power transmissions, particularly those using planetary geararrangements, require a hydraulic system to provide controlledengagement and disengagement, on a desired schedule, of the clutches andbrakes or torque transmitting mechanisms that operate to establish theratios within the planetary gear arrangement.

These control systems have evolved from substantially pure hydrauliccontrol systems, wherein hydraulic devices produce all of the controlsignals to electro-hydraulic control systems, wherein an electroniccontrol unit produces a number of the control signals. The electroniccontrol unit emits electrical control signals to solenoid valves, whichthen issue controlled hydraulic signals to the various operating valveswithin the transmission control.

With many of the early pure hydraulic and first generationelectro-hydraulic control systems, the power transmission utilized anumber of freewheel or one-way devices which smooth the shifting orratio interchange of the transmission during both upshifting anddownshifting of the transmission. This relieves the hydraulic controlsystem from providing for the control of overlap between the torquetransmitting mechanism that was coming on and the torque transmittingmechanism that was going off. If this overlap is excessive, the driverfeels a shudder in the drivetrain, and if the overlap is too little, thedriver experiences engine flare or a sense of coasting. The freewheeldevice prevents this feeling by quickly engaging when the torque imposedthereon is reversed from a freewheeling state to a transmitting state.

The advent of electro-hydraulic devices gave rise to what is known asclutch-to-clutch shift arrangements to reduce the complexity of thetransmission and the control. These electro-hydraulic control mechanismsare generally perceived to reduce cost and reduce the space required forthe control mechanism.

In addition, with the advent of more sophisticated control mechanisms,the power transmissions have advanced from two-speed or three-speedtransmissions to five-speed and six-speed transmissions. In at least onepresently available six-speed transmission, just five friction devicesare employed to provide six forward speeds, neutral condition, and areverse speed. Such a gear arrangement is shown in U.S. Pat. No.4,070,927 issued to Polak on Jan. 31, 1978. The use of the planetarygearset shown in the Polak patent has given rise to a number ofelectro-hydraulic control mechanisms, such as that shown in U.S. Pat.No. 5,601,506, issued to Long et al. on Feb. 11, 1997. The torquecapacity of a torque transmitting mechanism (on-coming or off-going)involved in a shift may be conveniently controlled by the combination ofan electrically activated solenoid valve and a pressure regulator valveor trim valve, as disclosed, for example, in the U.S. Pat. No. 5,911,244to Long et al., issued on Jun. 15, 1999, assigned to the assignee of thepresent invention, and incorporated herein by reference. In a typicalsystem, the solenoid valve is activated by pulse-width-modulation (PWM)at a controlled duty cycle to develop a pilot pressure for the pressureregulator valve or trim valve, which in turn, supplies fluid pressure tothe torque transmitting mechanisms in proportion to the solenoid dutycycle.

Additionally, an electrically variable hybrid transmission has beenproposed to improve fuel economy and reduce exhaust emissions. Theelectrically variable hybrid transmission splits mechanical powerbetween an input shaft and an output shaft into a mechanical power pathand an electrical power path by means of differential gearing. Themechanical power path may include clutches and additional gears. Theelectrical power path may employ two electrical power units, ormotor/generator assemblies, each of which may operate as a motor or agenerator. With an electrical storage system, such as a battery, theelectrically variable hybrid transmission can be incorporated into apropulsion system for a hybrid electric vehicle. The operation of suchan electrically variable hybrid transmission is described in the U.S.Pat. No. 6,551,208 to Holmes et al., issued on Apr. 22, 2003 and herebyincorporated by reference in its entirety.

The hybrid propulsion system uses an electrical power source as well asan engine power source. The electrical power source is connected withthe motor/generator units through an electronic control unit, whichdistributes the electrical power as required. The electronic controlunit also has connections with the engine and vehicle to determine theoperating characteristics, or operating demand, so that themotor/generator assemblies are operated properly as either a motor or agenerator. When operating as a generator, the motor/generator assemblyaccepts power from either the vehicle or the engine and stores power inthe battery, or provides that power to operate another electrical deviceor another motor/generator assembly.

It is important to reliably and inexpensively provide torquetransmitting mechanism engagement and disengagement in the abovedescribed torque transmitting mechanism controls to enable shiftprogression. Historically, the engagement and disengagement has beenaccomplished by placing a torque transmitting mechanism in selectivefluid communication with a dedicated trim valve. The trim valve isoperable to provide engagement control to the torque transmittingmechanism only, so additional torque transmitting mechanisms would needadditional discrete trim valves to effect engagement.

SUMMARY OF THE INVENTION

The present invention provides an improved electro-hydraulic controlsystem having a multiplexed (one source controlling multiple functions)trim system for an electrically variable hybrid transmission. Themultiplexed trim system of the present invention allows engagementcontrol of four torque transmitting mechanism and individual control offluid flow to effect cooling of two motor/generators by multiplexingthree trim valves with two logic valves.

A trim valve system for an electrically variable hybrid transmission isprovided having at least one trim valve operable to selectivelycommunicate pressurized fluid to at least one logic valve and at leastone torque transmitting mechanism in selective fluid communication withthe at least one logic valve. Additionally, at least one motor/generatorunit is provided in selective fluid communication with the at least onelogic valve and operable to receive pressurized fluid to effect coolingof the at least-one motor/generator unit. The trim valve system ischaracterized by the number of the at least one trim valves being fewerthan the sum of the at least one torque transmitting mechanism land theat least one motor/generator unit.

The at least one logic valve of the present invention may have a firstposition and a second position. One of the at least one logic valve maybe operable to direct pressurized fluid from one of the at least onetrim valve to one of the at least one torque transmitting mechanism orone of the at least one motor/generator unit when the one of the atleast one logic valve is in the first position. Alternately, the one ofthe at least one logic valve may be operable to direct pressurized fluidfrom the one of the at least one trim valve to another of the at leastone-torque transmitting mechanism or the one of the motor/generator unitwhen the one of the at least one logic valve is in the second position.The at least one trim valve may be controlled by a variable pressuresolenoid valve and the at least one trim valve can be a variablepressure regulator valve.

In another aspect of the present invention, a trim valve system for anelectrically variable hybrid transmission is provided having a firstlogic valve. The first logic valve has a first position and a secondposition and is operable to selectively distribute pressurized fluid toa first and a second torque transmitting mechanism to selectively effectengagement of the first and the second torque transmitting mechanisms.Additionally, a second logic valve having a first position and a secondposition and being operable to selectively distribute pressurized fluidto a first and a second motor/generator to selectively effect thecooling of the first and the second motor/generator. The second logicvalve is operable to selectively distribute pressurized fluid to a thirdand a fourth torque transmitting mechanism to selectively effectengagement of the third and the fourth torque transmitting mechanisms. Afirst trim valve operable to selectively distribute pressurized fluid tothe second logic valve is provided. A second trim valve operable toselectively distribute pressurized fluid to the first and the secondlogic valve is provided. A third trim valve operable to selectivelydistribute pressurized fluid to the first logic valve is provided. Thefirst and second logic valves are in selective fluid communication withone another and the first, second, and third trim valves selectivelycommunicate pressurized fluid to the first and second logic valves toselectively provide engagement of the first, second, third, and fourthtorque transmitting mechanisms and to selectively provide cooling to thefirst and second motor/generators. The first, second, and third trimvalves and the first and second logic valves are connected in amultiplexed arrangement such that there are fewer of the trim valvesthan the sum of the torque transmitting mechanisms and themotor/generators.

The first trim valve may be operable to selectively control the coolingof the first motor/generator, while the second trim valve may beoperable to selectively control the cooling of the secondmotor/generator, and the third trim valve may be operable to control theengagement of the first torque transmitting mechanism when the first andsecond logic valves are in the first position.

The first trim valve may be operable to selectively control the coolingof the first motor/generator, while the second trim valve may beoperable to selectively control the engagement of the second torquetransmitting mechanism, and the third trim valve is operable to controlthe cooling of the second motor/generator when the first logic valve isin the second position and the second logic valve is in the firstposition.

The first trim valve may be operable to selectively control theengagement of the fourth torque transmitting mechanism, while the secondtrim valve may be operable to selectively control the engagement of thesecond torque transmitting mechanism, and the third trim valve may beoperable to control the engagement of the first torque transmittingmechanism when the first logic valve is in the first position and thesecond logic valve is in the second position.

The first trim valve may be operable to selectively control theengagement of the fourth torque transmitting mechanism, while the secondtrim valve may be operable to selectively control the engagement of thesecond torque transmitting mechanism, and the third trim valve may beoperable to control the engagement of the third torque-transmittingmechanism when the first logic valve is in the second position and thesecond logic valve is in the second position.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a electrically variable hybridvehicular powertrain for use with the present invention; and

FIGS. 2 a and 2 b, taken together, represent a schematic representationdescribing the electro-hydraulic control system utilized with thepowertrain of FIG. 1, depicting the control system in an electricalpower ON, park/neutral mode of operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings wherein like characters represent the same orcorresponding parts throughout the several views, there is seen in FIG.1 a powertrain 10 having an engine 12, an electrically variable hybridtransmission 14, and a final drive 16.

The engine 12 is an internal combustion engine. The electricallyvariable hybrid transmission 14 includes a planetary gear arrangementhaving an input shaft 18, an output shaft 20, three planetary gearsets22, 24, and 26, four torque transmitting mechanisms C1, C2, C3, and C4,and an electro-hydraulic control system 28. The torque transmittingmechanisms C2 and C4 are fluid-operated rotating clutch-type devices,while the torque transmitting mechanisms C1 and C3 are fluid-operatedstationary clutch or brake devices. The selective engagement anddisengagement of the torque transmitting devices is controlled by anelectro-hydraulic control system 28, which is shown in FIGS. 2 a and 2b.

Further incorporated into the electrically variable hybrid transmission14 is a pair of electrical power units or motor/generators 30 or A and32 or B that are controlled by an electronic control unit 34. Theelectronic control unit 34 is connected with the electrical power unit30 through three electrical conductors 36, 37, and 38 and is connectedwith the electrical power unit 32 through three electrical conductors40, 41, and 42. The electronic control unit 34 is also in electricalcommunication with an electrical storage device 44, which is connectedwith the electronic control unit 34 through a pair of electricalconductors 46 and 48. The electrical storage device 44 is generally oneor more electrical batteries.

The electrical power units 30 and 32 are preferably motor/generatorunits, which can operate as a power supplier or as a power generator.When operating as a motor or power supplier, the electrical power units30 and 32 will supply power to the electrically variable hybridtransmission 14. When operating as generators, the electrical powerunits 30 and 32 will take electrical power from the transmission, andthe electronic control unit 34 will either distribute the power to theelectrical storage device 44 or distribute the power to the other powerunit, which will be operating as a motor at that time.

The electronic control unit 34 receives a number of electrical signalsfrom the vehicle and transmission, such as engine speed, throttle angle,vehicle speed, to name a few. These electrical signals are used as inputsignals for a programmable digital computer, which is incorporatedwithin the electronic control unit 34. The computer is then effective todistribute the electrical power as required to permit the operation ofthe electrically variable hybrid transmission 14 in a controlled manner.

The planetary gear arrangement, as shown in FIG. 1, provides fourforward speed ratios or ranges between the input shaft 18 and the outputshaft 20. In the first forward range, the torque transmitting mechanismsC1 and C4 are engaged. In the second forward range, the torquetransmitting mechanisms C1 and C2 are engaged. In the third forwardrange, the torque transmitting mechanisms C2 and C4 are engaged. In thefourth forward range, the torque transmitting mechanisms C2 and C3 areengaged. The gearing also provides a park/neutral condition when thetorque transmitting mechanisms C1, C2, C3 and C4 are disengaged. Anelectrically variable low mode of operation is provided wherein thetorque transmitting mechanism C1 is engaged, and an electricallyvariable high mode of operation is provided wherein the torquetransmitting mechanism C2 is engaged.

The powertrain 10 may operate in a purely electric mode. The engine off,electric low speed mode of operation is facilitated by engaging the C1torque transmitting mechanism. The powertrain 10 has two speed ranges ofdrive-home capabilities within the electrically variable hybridtransmission 14 in the event that the electro-hydraulic control system28 undergoes a malfunction or discontinuance of electrical power. In theelectrical power off drive home modes, the electro-hydraulic controlsystem 28 defaults to an electrically variable low mode of operationwherein the torque transmitting mechanism C1 is engaged, and anelectrically variable high mode of operation wherein the torquetransmitting mechanism C2 is engaged. The electrically variable hybridtransmission 14 is capable of operating in a parallel reverse mode ofoperation. In the parallel reverse mode, the electrically variablehybrid transmission 14 operates in an electrically variable low mode ofoperation wherein the torque transmitting mechanism C1 is engaged.

The electro-hydraulic control system 28 includes an electronic controlunit (ECU) and a hydraulic control unit (HYD). The ECU incorporates aconventional digital computer that is programmable to provide electricalsignals to the hydraulic portion of the electro-hydraulic control system28 to establish the engagement and disengagement of the torquetransmitting mechanisms C1, C2, C3, and C4. FIGS. 2 a and 2 b, takentogether, show the electro-hydraulic control system 28 in detail. Asshown in FIGS. 2 a and 2 b, the hydraulic portion of theelectro-hydraulic control system 28 includes a hydraulic pump 50, suchas a variable displacement pump, that draws fluid from the reservoir 52for delivery to a main passage 54. Alternately, an electricallycontrolled hydraulic pump 56 is provided for operation in the electricmode. A check valve 58 operates to selectively distribute pressurizedfluid to the main passage 54 depending upon which pump 50 or 56 isoperating. A relief valve 60 is provided in fluid communication with anoutlet passage 62 of the hydraulic pump 50 to guard against overpressurization of the main passage 54 when the hydraulic pump 50 isoperating. Likewise, a relief valve 64 is provided in fluidcommunication with an outlet passage 66 of the electrically controlledhydraulic pump 56 to guard against over pressurization of the mainpassage 54 when the electrically controlled hydraulic pump 56 isoperating. The pressure relief valves 60 and 64 will exhaust should anover pressurized condition manifest itself within the main passage 54.The main passage 54 is in fluid communication with an electronictransmission range selection (ETRS) valve 68, an actuator feed regulatorvalve 70, a damper lock-out clutch trim valve 72, a trim valve 74, atrim valve 76, and a trim valve 78.

A line regulator valve 80 communicates with pressurized fluid within theoutlet passage 62 when the hydraulic pump 50 is operating. The lineregulator valve 80 establishes the pressure within the main passage 54,and a portion of that fluid is delivered to a passage 82, whichcommunicates with a cooler regulator valve 84. The fluid exiting thecooler regulator valve 84 communicates with an auxiliary pump regulatorvalve 86 via a passage 88. When the auxiliary pump regulator valve 86 isin a spring set position, fluid within the passage 88 is allowed to passinto a cooler 90 and/or a cooler bypass valve 92. The cooler bypassvalve 92 is operable to provide fluid flow in the event that fluidpassage through the cooler 90 is blocked. The fluid from the cooler 90and/or cooler bypass valve 92 is then distributed to a lubricationsystem regulator valve 94. The lubrication system regulator valve 94operates to distribute pressurized fluid to the lubrication system 96 ofthe electrically variable hybrid transmission 14. In practice, only oneof the cooler regulator valve 84 and the lubrication system regulatorvalve 94 may be necessary for proper functioning of theelectro-hydraulic control system 28.

Alternately, the auxiliary pump regulator valve 86 communicates withpressurized fluid within the outlet passage 66 when the electricallycontrolled hydraulic pump 56 is operating. The auxiliary pump regulatorvalve 86 establishes the pressure within the main passage 54, and whenthat pressure is satisfied, fluid is allowed to pass into the cooler 90and/or the cooler bypass valve 92. The cooler bypass valve 92 isoperable to provide fluid flow in the event that fluid passage throughthe cooler 90 is blocked. The fluid from the cooler 90 and/or coolerbypass valve 92 is then distributed to a lubrication system regulatorvalve 94. The lubrication system regulator valve. 94 operates todistribute pressurized fluid to the lubrication system 96 of theelectrically variable hybrid transmission 14.

The ETRS valve 68 operates to selectively communicate pressurized fluidfrom the main passage 54 to a servo 98 via a passage 100. When the ETRSvalve 68 is in a, pressure set position, the pressurized fluid withinthe main passage 54 is introduced to the servo 98 via the passage 100.When the fluid pressure within the servo 98 is sufficient to overcomethe bias of a spring 102, a piston 104, interconnected with a park pawlmechanism 106 via a link 108, moves within the servo 98 therebydisengaging the park pawl mechanism 106. When the ETRS valve 68 is inthe spring set position, shown in FIG. 2 a, a land 110 blocks the flowof pressurized fluid from the main passage 54, and the passage 100 willexhaust.

The actuator feed regulator valve 70 reduces the pressure within themain passage 54 to a control pressure within a passage 112 and a passage114. The fluid within the passage 112 communicates with a plurality ofsolenoid valves 116, 118, 120, 122, 124, 126, and 128. The fluid withinthe passage 114 communicates with a solenoid valve 130. The solenoidvalves 124 and 126 are on/off type solenoid valves, while the solenoidvalves 116, 118, 120, 122, 128, and 130 are variable pressure typesolenoid valves. The solenoid valves 120, 122, and 128 are normally highor normally open type solenoid valves, while the remaining solenoidvalves 116, 118, 124, 126, and 130 are normally low or normally closedtype solenoid valves. A normally open solenoid valve will distributeoutput pressure in the absence of an electrical signal to the solenoid.

The solenoid valve 116 is operable to provide an output pressure inpassage 132 that controls the bias pressure or control pressure on thedamper lock-out clutch trim valve 72. The damper lock-out clutch trimvalve 72 is operable to selectively engage a damper lock-out clutch 134when transitioning into and out of the electric mode of operation.

The solenoid valve 118 is operable to provide an output pressure in apassage 136 that controls the bias pressure on the trim valve 74. Thesolenoid valve 120 is operable to provide an output pressure in passage138 that controls the pressure bias on the trim valve 76. The solenoidvalve 122 is operable to provide an output pressure in a passage 140that controls the pressure bias on the trim valve 78. Additionally, theoutput pressure within passage 140 controls the pressure bias on a boostvalve 142 and is further communicated to a logic valve 144. With thepassage 140 pressurized, the boost valve 142 is biased to a pressure setposition. Alternately, with the passage 140 exhausted, the boost valve142 will move to a spring set position, as shown in FIG. 2 b. The trimvalves 72, 74, 76, and 78 are selectively biased into a second positionor a pressure set position by fluid pressure within their respectivepassages 132, 136, 138, and 140. When the passages 132, 136, 138, and140 exhaust, their respective trim valves 72, 74, 76, and 78 move to afirst position or a spring set position. Additionally, the trim valves72, 74, 76, and 78 have a trim or pressure regulation position.

The solenoid valve 128 is operable to provide an output pressure inpassage 146 that controls pressure bias to the line regulator valve 80.The solenoid valve 128, by modulating the fluid pressure within passage146, is operable to vary the operating characteristics of the lineregulator valve 80 thereby modulating the pressure value within the mainpassage 54 for torque based pressure control. The solenoid valve 130 isoperable to provide an output pressure in passage 147, which operates tode-latch the ETRS valve 68 and place the ETRS valve 68 in a spring setposition.

The solenoid valve 124 is operable to provide an output pressure inpassage 148 that controls the pressure bias on the logic valve 144.Additionally, the output pressure in passage 148 communicatespressurized fluid to the ETRS valve 68 and is operable to selectivelybias the ETRS valve 68 into a pressure set position by engaging adifferential area 149 on a land 150. The logic valve 144 has adifferential area 152 operable to latch the logic valve 144 in apressure set position when the electrical power to the solenoid valve124 is interrupted. Pressurized fluid within the passage 140 providesthe differential area 152 with the force necessary to bias the logicvalve 144 in a pressure set position. The solenoid valve 126 is operableto provide an output pressure in passage 154 that controls the pressurebias on a logic valve 156. The output pressure in the passage 154 isalso communicated to the trim valves 74 and 76. Logic valves 144 and 156each have a first position or a spring set position, and a secondposition or a pressure set position.

The logic valves 144 and 156 multiplex the trim valves 74, 76, and 78 toprovide control to the four torque transmitting mechanisms C1, C2, C3,and C4. The logic valve 144 selectively communicates pressurized fluidto control the engagement of the torque transmitting mechanisms C1 andC2. While the logic valve 156 selectively communicates pressurized fluidto control the engagement of the torque transmitting mechanisms C3 andC4. The multiplexed trim valve configuration also provides control offluid flow to effect cooling of the motor/generator 30 andmotor/generator 32.

The trim valve 74 selectively communicates pressurized fluid through anoutlet passage 158 to the logic valve 156. The outlet passage 158communicates pressurized fluid to a passage 160 through a flow controlorifice 162. The passage 160 is operable to provide pressurized fluid tobias the ETRS valve 68 into a pressure set position. The trim valve 76selectively communicates pressurized fluid through an outlet passage 164to both logic valves 144 and 156. An outlet passage 166 of the trimvalve 78 selectively communicates pressurized fluid to the logic valve144. Additionally, the trim valve 78 selectively communicatespressurized fluid to the boost valve 142 through an outlet passage 168.The logic valves 144 and 156 are in selective fluid communication withone another through passages 170, 172, and 174.

A backfill passage 176 is in fluid communication with the actuator feedregulator valve 70, the damper lock-out clutch trim valve 72, the trimvalve 74, the trim valve 76, the trim valve 78, the logic valve 144, andthe logic valve 156. The passage 112 communicates pressurized fluid tothe backfill passage 176 through a series of flow restricting orifices178. The fluid pressure within the backfill passage 176 is maintained ata value of approximately two pounds per square inch (psi) by a back fillregulator valve 180 to prevent air from entering the electro-hydrauliccontrol system 28.

An exhaust passage 181 is in communication with the damper lock-outclutch trim valve 72, the trim valves 74, 76, and 78, and the boostvalve 142. Pressurized fluid within feedback passage 182 is operable toprovide a force balance when the damper lock-out clutch trim valve 72 isin the pressure regulation or trim position. The feedback passage 182also communicates pressurized fluid to the auxiliary pump regulatorvalve 86 to modulate the pressure within the main passage 54 when theelectrically controlled hydraulic pump 56 is operating. Likewise,pressurized fluid within a feedback passage 184 is operable to provide aforce balance when the trim valve 74 is in the trim position.Pressurized fluid within a feedback passage 186 is operable to provide aforce balance when the trim valve 76 is in the trim position.Additionally, pressurized fluid within a feedback passage 188 isoperable to provide a force balance when the trim valve 78 is in thetrim position and the boost valve 142 is in the spring set position.Alternately, when the boost valve 142 is in the pressure set position,the feedback passage 188 is exhausted.

The main passage 54 communicates pressurized fluid to a passage 190though a series of flow restricting orifices 192. By providing fluidflow to the passage 190, the motor/generator 30 is provided with ameasured amount of fluid flow to effect the cooling of themotor/generator 30. When additional fluid is required to cool themotor/generator 30, a passage 194 is selectively pressurized with fluidby the logic valve 156. Similarly, the main passage 54 communicatespressurized fluid to a passage 196 though a series of flow restrictingorifices 198. By providing fluid flow to passage 196, themotor/generator 32 is provided with a measured amount of fluid flow toeffect the cooling of the motor/generator 32. When additional fluid isrequired to cool the motor/generator 32, a passage 200 is selectivelypressurized with fluid by the logic valve 156.

With the logic valves 156 and 144 in the spring set position, such aswhen operating in the electric and electrically variable low mode, thetrim valve 76 is operable to selectively provide additional pressurizedfluid to cool the motor/generator 32. Additionally, the trim valve 78 isoperable to selectively provide pressurized fluid to effect engagementof the torque transmitting mechanism C1, while the trim valve 74 isoperable to selectively provide additional pressurized fluid to cool themotor/generator 30.

With the logic valve 156 in the spring set position and the logic valve144 in the pressure set position, such as when operating in the electricand electrically variable high mode, the trim valve 76 is operable toselectively provide pressurized fluid to effect engagement of the torquetransmitting mechanism C2. Additionally, the trim valve 78 is operableto selectively provide additional pressurized fluid to cool themotor/generator 32, while the trim valve 74 is operable to selectivelyprovide additional pressurized fluid to cool the motor/generator 30.

With the logic valve 156 in the pressure set position and the logicvalve 144 in the spring set position, such as when operating in thefirst, second, and third forward range mode, the trim valve 76 isoperable to selectively provide pressurized fluid to effect engagementof the torque transmitting mechanism C2. Additionally, the trim valve 78is operable to selectively provide pressurized fluid to effectengagement of the torque transmitting mechanism C1, while the trim valve74 is operable to selectively provide pressurized fluid to effectengagement of the torque transmitting mechanism C4.

With the logic valve 156 in the pressure set position and the logicvalve 144 in the pressure set position, such as when operating in thethird and fourth forward range mode, the trim valve 76 is operable toselectively provide pressurized fluid to effect engagement of the torquetransmitting mechanism C2. Additionally, the trim valve 78 is operableto selectively provide pressurized fluid to effect engagement of thetorque transmitting mechanism C3, while the trim valve 74 is operable toselectively provide pressurized fluid to effect engagement of the torquetransmitting mechanism C4.

Four pressure sensitive switches or pressure switches PS1, PS2, PS3, andPS4 are provided for position detection of the trim valves 74, 76, and78 and the logic valves 144 and 156. The ability to monitor the abovementioned valves and detect any change, or lack of change, in valvestate is of importance in order to provide continuous and reliableoperation of the electrically variable hybrid transmission 14.

The electro-hydraulic control system 28 is capable of detecting statechanges of the trim valves 74, 76, and 78 and the logic valves 144 and156 by multiplexing the four pressure switches PS1, PS2, PS3, and PS4.The pressure switches PS1, PS2, PS3, and PS4 are disposed in selectivefluid communication with the logic valve 144 and the trim valves 76, 78,and 74, respectively. Additionally, the pressure switches PS2 and PS4communicate with the logic valve 156 through the trim valves 74 and 76.Traditionally, five pressure switches, one switch for each valve, wouldhave been used to determine valve state changes.

Detection of a state change, or failure to change, of the logic valve144 is accomplished through stand-alone detection using the pressureswitch PS1. With the logic valve 144 in the spring set position, thepressure switch PS1 will exhaust. When the logic valve 144 moves to thepressure set position, a land 202 will block the pressure switch PS1from exhausting. The passage 112 will communicate pressurized fluid tothe pressure switch PS1 through orifices 204. Detection of a statechange, or failure to change, of the trim valve 78 is accomplishedthrough stand-alone detection using the pressure switch PS3. With thetrim valve 78 in the spring set position, the passage 112 willcommunicate pressurized fluid to the pressure switch PS3. When the trimvalve 78 moves to the pressure set position, a land 205 will block thepassage 112 thereby allowing the pressure switch PS3 to exhaust to thebackfill passage 176.

Detection of a state change or failure to change, of the logic valve 156and the trim valves 76 and 74 is achieved by multiplexing the pressureswitches PS2 and PS4. To achieve this, passage 206 is disposed in fluidcommunication with the trim valves 74 and 76 and, the logic valve 156.Additionally, the passage 154 is disposed in fluid communication withthe trim valves 74 and 76 and the logic valve 156. The passages 206 and154 are selectively pressurized based on the position of the logic valve156. When the logic valve 156 is in the spring set position, the passage206 is pressurized with fluid from passage 112 through orifices 208since the fluid cannot exhaust through the backfill passage 176 due tothe position of the logic valve 156. Alternately, when the logic valve156 is in the pressure set position, the pressurized fluid withinpassage 206 will exhaust via the backfill passage 176. When the solenoidvalve 126 is energized, the logic valve 156 moves to a pressure setposition and the passage 154 will pressurize. Alternately, when thesolenoid valve 126 is de-energized, the logic valve 156 will move to thespring set position and the passage 154 will exhaust.

This multiplexed system provides a reversal in states of pressurizationbetween the passage 206 and 154. For example, if the logic valve 156 isin the pressure set position, the passage 154 will be pressurized andthe passage 206 will exhaust. Alternately, if the logic valve 156 is inthe spring set position, the passage 206 will be pressurized and thepassage 154 will exhaust. This event will be indicated through a changein pressure state of both of the pressure switches PS2 and PS4irrespective of the position of their respective trim valves 76 and 74.Changes in state of one of the trim valves 74 and 76 will result in onlya single change in pressure switch state.

Park/Neutral Mode of Operation

When a park/neutral condition, as shown in FIGS. 2 a and 2 b, isrequested the solenoid valve 130 will pressurize the passage 147,thereby pressurizing a spring pocket 210 of the ETRS valve 68. Thepressurized fluid within the spring pocket 210 will de-latch the ETRSvalve 68 placing it in a spring set position, as shown in FIG. 2 a. Withthe ETRS valve 68 in the spring set position, the flow of pressurizedfluid within the main passage 54 to passage 100 is blocked by the land110. The passage 100 will exhaust allowing the spring 102 to bias thepiston 104 of the servo 98. With the servo 98 in the spring biasedposition, the park pawl mechanism 106 is engaged by the link 108.

When disengagement of the park pawl mechanism 106 is desired, the fluidpressure within the passage 147 and the spring pocket 210 is exhausted.The ETRS valve 68 may be placed in the pressure set position in one oftwo ways. The trim valve 74 may selectively bias the ETRS valve 68 intoa pressure set position by pressurizing the passage 160 via passage 158.The trim valve 74 must be in the trim or pressure set position tocontrol the ETRS valve 68. Additionally, the solenoid valve 124 mayselectively pressurize the passage 148 causing fluid pressure to act onthe differential area 149 formed on the land 150. Once pressure withinpassage 160 and/or passage 148 is of a large enough magnitude toovercome the spring bias of the ETRS valve 68, the ETRS valve 68 willmove to a pressure set position. The ETRS valve 68 will remain latchedin the pressure set position by the pressurized fluid within the mainpassage 54 acting upon the land 110, until de-latched by increasing thepressure within the spring pocket 210 via the passage 147. With the ETRSvalve 68 in the pressure set position, the pressurized fluid within themain passage 54 will pressurize the passage 100, thereby biasing thepiston 104 of the servo 98 against the force of the spring 102. With theservo 98 in the pressure set position, the park pawl mechanism 106 willdisengage.

FIGS. 2 a and 2 b collectively represent the electro-hydraulic controlsystem 28 in an electrical power ON park/neutral mode of operation. Inthis mode, the park pawl mechanism 106 is engaged. For all other modesof operation, the park pawl mechanism 106 is disengaged. The logicvalves 144 and 156 are in a spring set position. The torque transmittingmechanisms C1, C2, C3 and C4 will exhaust to the backfill passage 176.Pressurized fluid within the passage 206 communicates with the trimvalve 74 to direct the pressure switch PS4 to report a high pressurestate for diagnostic purposes. Similarly, pressurized fluid within thepassage 112 communicates with the trim valve 78 to direct the pressureswitch PS3 to report a high pressure state for diagnostic purposes,while the pressure switches PS1 and PS2 will report a low pressure statefor diagnostic purposes.

Additionally, the trim valves 72, 74, 76, and 78 remain in the springset position for this mode of operation. The motor/generator 30 andmotor/generator 32 will receive pressurized fluid from the main passage54 for cooling-purposes.

Engine Off Electric Mode of Operation

When operating in an engine OFF electric mode of operation, the internalcombustion engine 12, shown in FIG. 1, is shut off and the hybridvehicle will rely solely on the electrical storage device 44 to powerthe motor/generators 30 and 32 to effect movement of the vehicle. As aresult, the hydraulic pump 50 will no longer provide pressurized fluidto the main passage 54. Instead, the electrically controlled hydraulicpump 56 will provide fluid pressure to bias the check valve 58 andpressurize the main passage 54. The damper lock-out clutch trim valve 72will bias to the pressure set position allowing pressurized fluid withinthe main passage 54 to effect engagement of the damper lock-out clutch134. The damper lock-out clutch 134 is operable to prevent the torsionalresonance associated with starting and stopping the engine 12 from beingtransmitted though the powertrain 10.

Additionally, the pressurized fluid within the outlet passage 66 iscommunicated to the auxiliary pump regulator valve 86 placing it in aregulating position. The auxiliary pump regulator valve 86 will provideexcess fluid flow to the lubrication system 96.

In the electric low speed mode of operation, the logic valves 144 and156 remain in the spring set position. The trim valve 78 is pressure setby energizing the solenoid valve 122. The trim valves 74 and 76 areplaced in the trim position by energizing the solenoid valves 118 and120, respectively. With the above stated valve configuration, the torquetransmitting mechanisms C2, C3, and C4 will exhaust, while the torquetransmitting mechanism C1 will engage. To effect engagement of thetorque transmitting mechanism C1, pressurized fluid from the mainpassage 54 is communicated to the outlet passage 166 of the trim valve78. The logic valve 144 will communicate the fluid within the outletpassage 166 to the torque transmitting mechanism C1. The trim valve 74communicates pressurized fluid from the main passage 54 to the outletpassage 158. The logic valve 156 communicates pressurized fluid from theoutlet passage 158 to the passage 194, thereby providing additionalfluid flow to cool the motor/generator 30. The trim valve 76communicates pressurized fluid from the main passage 54 to the outletpassage 164. The logic valve 156 communicates pressurized fluid from theoutlet passage 164-to the passage 170. The logic valve 144 communicatespressurized fluid from the passage 170 to the passage 172. Subsequently,the logic valve 156 communicates pressurized fluid from the passage 172to the passage 200, thereby providing additional fluid flow to cool themotor/generator 32.

The pressurized fluid within the passage 206 communicates with the trimvalve 74 to direct the pressure switch PS4 to report a high pressurestate for diagnostic purposes. The pressure switches PS1, PS2, and PS3report a low pressure state for diagnostic purposes.

Electrically Variable Low Speed Mode of Operation

When operating in the electrically variable low speed mode of operation,the internal combustion engine 12 and the motor/generators 30 and 32work in concert to effect movement of the vehicle. This continuouslyvariable mode of operation employs the torque transmitting mechanism C1in conjunction with the motor/generators 30 and 32. All garage shifts,i.e. neutral to reverse, reverse to neutral, neutral to drive, and driveto neutral, are performed while in the electrically variable, low speedmode of operation.

In this mode, the trim valve 78 is pressure set by energizing thesolenoid valve 122. The trim valves 74 and 76 are placed in the trimposition by energizing the solenoid valves 118 and 120, respectively.With the above stated valve configuration, the torque transmittingmechanisms C2, C3, and C4 will exhaust, while the torque transmittingmechanism C1 will engage. To effect engagement of the torquetransmitting mechanism C1, pressurized fluid from the main passage 54 iscommunicated to the outlet passage 166 of the trim valve 78. The logicvalve 144 communicates the fluid within the outlet passage 166 to thetorque transmitting mechanism C1. The trim valve 74 communicatespressurized fluid from the main passage 54 to the outlet passage 158.The logic valve 156 communicates pressurized fluid from the outletpassage 158 to the passage 194, thereby providing additional fluid flowto cool the motor/generator 30. The trim valve 76 communicatespressurized fluid from the main passage 54 to the outlet passage 164.The logic valve 156 communicates pressurized fluid from the outletpassage 164 to the passage 170. The logic valve 144 communicatespressurized fluid from the passage 170 to the passage 172. Subsequently,the logic valve 156 communicates pressurized fluid from the passage 172to the passage 200, thereby providing additional fluid flow to cool themotor/generator 32.

The pressurized fluid within the passage 206 communicates with the trimvalve 74 to direct the pressure switch PS4 to report a high pressurestate for diagnostic purposes. The pressure switches PS1, PS2, and PS3report a low pressure state for diagnostic purposes.

Electrically Variable High Speed Mode of Operation

When operating in the electrically variable high speed mode ofoperation, the internal combustion engine 12 and the motor/generators 30and 32 work in concert to effect movement of the vehicle. Thiscontinuously variable mode of operation employs the torque transmittingmechanism C2 in conjunction with the motor/generators 30 and 32. Thelogic valve 144 is pressure set by energizing the solenoid valve 124,while the logic valve 156 remains in the spring set position.

The trim valve 76 is pressure set by energizing the solenoid valve 120.The trim valves 74 and 78 are placed in the trim position by energizingthe solenoid valves 118 and 122, respectively. With the above statedvalve configuration, the torque transmitting mechanisms C1, C3, and C4will exhaust, while the torque transmitting mechanism C2 will engage. Toeffect engagement of the torque transmitting mechanism C2, the trimvalve 76 communicates pressurized fluid within the main passage 54 tothe outlet passage 164, which is in fluid communication with the logicvalve 144. The logic valve 144 communicates the pressurized fluid withinthe outlet passage 164 to the torque transmitting mechanism C2. The trimvalve 74 communicates pressurized fluid from the main passage 54 to theoutlet passage 158. The logic valve 156 communicates pressurized fluidfrom the outlet passage 158 to the passage 194, thereby providingadditional fluid flow to cool the motor/generator 30. The trim valve 78communicates pressurized fluid from the main passage 54 to the outletpassage 166. The logic valve 144 communicates pressurized fluid from theoutlet passage 166 to the passage 172. The logic valve 156 communicatespressurized fluid from the passage 172 to the passage 200, therebyproviding additional fluid flow to cool the motor/generator 32.

Pressurized fluid within the passage 206 communicates with the trimvalves 74 and 76 to direct the pressure switches PS4 and PS2,respectively, to report a high pressure state for diagnostic purposes.Pressurized fluid within the passage 112 communicates with the trimvalve 78 to direct the pressure switch PS3 to report a high pressurestate for diagnostic purposes. Additionally, pressurized fluid withinthe passage 112 communicates with the pressure switch PS1 through theorifices 204 to direct the pressure switch PS1 to report a high pressurestate for diagnostic purposes.

First Forward Range Mode of Operation

When operating in the first forward range mode of operation, the logicvalve 156 is pressure set by energizing the solenoid valve 126 and thelogic valve 144 is in the spring set position.

The trim valves 74 and 78 are pressure set by energizing the solenoidvalves 116 and 122, respectively. The trim valve 76 is in the spring setposition. With the above stated valve configuration, the torquetransmitting mechanisms C2 and C3 will exhaust, while the torquetransmitting mechanisms C1 and C4 will engage. To effect engagement ofthe torque transmitting mechanism C1, the trim valve 78 communicatespressurized fluid within the main passage 54 to the outlet passage 166.The logic valve 144 communicates the fluid within the outlet passage 166to the torque transmitting mechanism C1. Additionally, to effectengagement of the torque transmitting mechanism C4, the trim valve 74communicates pressurized fluid within the main passage 54 to the outletpassage 158, which is in fluid communication with the logic valve 156.The logic valve 156 communicates the pressurized fluid within the outletpassage 158 to the torque transmitting mechanism C4.

Pressurized fluid within the passage 154 communicates with the trimvalves 74 and 76 to direct the pressure switches PS4 and PS2,respectively, to report a high pressure state for diagnostic purposes.The pressure switches PS1 and PS3 report a low pressure state fordiagnostic purposes. The motor/generator 30 and motor/generator 32receive pressurized fluid from the main passage 54 for cooling purposes.

Second Forward Range Mode of Operation

When operating in the second forward range mode of operation, the logicvalve 156 is pressure set by energizing the solenoid valve 126 and thelogic valve 144 is in the spring set position.

The trim valves 76 and 78 are pressure set by energizing the solenoidvalves 120 and 122, respectively. The trim valve 74 is in the spring setposition. With the above stated valve configuration, the torquetransmitting mechanisms C3 and C4 will exhaust, while the torquetransmitting mechanisms C1 and C2 will engage. To effect engagement-ofthe torque transmitting mechanism C1, pressurized fluid from the mainpassage 54 is communicated to the outlet passage 166 of the trim valve78. The logic valve 144 communicates the fluid within the outlet passage166 to the torque transmitting mechanism C1. Additionally, to effectengagement of the torque transmitting mechanism C2, the trim valve 76communicates pressurized fluid within the main passage 54 to the outletpassage 164, which is in fluid communication with the logic valve 156.The logic valve 156 communicates the pressurized fluid within the outletpassage 164 to the passage 174. The logic valve 144 communicates thefluid within passage 174 to the torque transmitting mechanism C2.

The pressure switches PS1, PS2, PS3, and PS4 report a low pressure statefor diagnostic purposes. The motor/generator 30 and motor/generator 32receive pressurized fluid from the main passage 54 for cooling-purposes.

Third Forward Range Mode of Operation

When operating in the third forward range mode of operation, the logicvalve 156 is pressure set by energizing the solenoid valve 126 and thelogic valve 144 is in the spring set position.

The trim valves 74 and 76 are pressure set by energizing the solenoidvalves 118 and 120, respectively. The trim valve 78 is in the spring setposition. With the above stated valve configuration, the torquetransmitting mechanisms C1 and C3 will exhaust, while the torquetransmitting mechanisms C2 and C4 will engage. To effect engagement ofthe torque transmitting mechanism C2, the trim valve 76 communicatespressurized fluid within the main passage 54 is communicated to theoutlet passage 164, which is in fluid communication with the logic valve156. The logic valve 156 communicates the pressurized fluid within theoutlet passage 164 to the passage 174. The logic valve 144 communicatesthe fluid within passage 174 to the torque transmitting mechanism C2.Additionally, to effect engagement of the torque transmitting mechanismC4, the trim valve 74 communicates pressurized fluid within the mainpassage 54 to the outlet passage 158, which is in fluid communicationwith the logic valve 156. The logic valve 156 communicates thepressurized fluid within the outlet passage 158 to the torquetransmitting mechanism C4

Pressurized fluid within the passage 154 communicates with the trimvalve 74 to direct the pressure switch PS4 to report a high pressurestate for diagnostic purposes. Additionally, pressurized fluid withinthe passage 112 communicates with the trim valve 78 to direct thepressure switch PS3 to report a high pressure state for diagnosticpurposes. The pressure switches PS1 and PS2 report a low pressure statefor diagnostic purposes. The motor/generator 30 and motor/generator 32receive pressurized fluid from the main passage 54 for cooling purposes.

An additional third forward range mode of operation is provided. Whenoperating in this mode of operation, the logic valve 156 is pressure setby energizing the solenoid valve 126 and the logic valve 144 is pressureset by energizing the solenoid valve 124.

The trim valves 74 and 76 are pressure set by energizing the solenoidvalves 118 and 120, respectively. The trim valve 78 is in the spring setposition. With the above stated valve configuration, the torquetransmitting mechanisms C1 and C3 will exhaust, while the torquetransmitting mechanisms C2 and C4 will engage. To effect engagement ofthe torque transmitting mechanism C2, pressurized fluid from the mainpassage 54 is communicated to the outlet passage 164 of the trim valve76, which is in fluid communication with the logic valve 144. The logicvalve 144 communicates the fluid within the outlet passage 164 to thetorque transmitting mechanism C2. Additionally, to effect engagement ofthe torque transmitting mechanism C4, the trim valve 74 communicatespressurized fluid within the main passage 54 to the outlet passage 158,which is in fluid communication with the logic valve 156. The logicvalve 156 communicates the pressurized fluid within the outlet passage158 to the torque transmitting mechanism C4

Pressurized fluid within the passage 154 communicates with the trimvalve 74 to direct the pressure switch PS4 to report a high pressurestate for diagnostic purposes. The pressurized fluid within the passage112 communicates with the trim valve 78 to direct the pressure switchPS3 to report a high pressure state for diagnostic purposes.Additionally, pressurized fluid within the passage 112 communicates withthe pressure switch PS1 through the orifices 204 to direct the pressureswitch PS1 to report a high pressure state for diagnostic purposes. Thepressure switch PS2 reports a low pressure state for diagnosticpurposes. The motor/generator 30 and motor/generator 32 receivepressurized fluid from the main passage 54 for cooling purposes.

Fourth Forward Range Mode of Operation

When operating in the fourth forward range mode of operation, the logicvalve 156 is pressure set by energizing the solenoid valve 126 and thelogic valve 144 is pressure set by energizing the solenoid valve 124.

The trim valves 76 and 78 are pressure set by energizing the solenoidvalves 120 and 122, respectively. The trim valve 74 is in the spring setposition. With the above stated valve configuration, the torquetransmitting mechanisms C1 and C4 will exhaust, while the torquetransmitting mechanisms C2 and C3 will engage. To effect engagement, ofthe torque transmitting mechanism C2, the trim valve 76 communicatespressurized fluid within the main passage 54 to the outlet passage 164,which is in fluid communication with the logic valve 144. The logicvalve 144 communicates the fluid within the outlet passage 164 to thetorque transmitting mechanism C2. Additionally, to effect engagement ofthe torque transmitting mechanism C3, the trim valve 78 communicatespressurized fluid within the main passage 54 to the outlet passage 166,which is in fluid communication with the logic valve 144. The logicvalve 144 communicates the pressurized fluid within the outlet passage166 to the passage 172. The logic valve 156 communicates the fluidwithin the passage 172 to the torque transmitting mechanism C3

Pressurized fluid within the passage 112 communicates with the pressureswitch PS1 through the orifices 204 to direct the pressure switch PS1 toreport a high pressure state for diagnostic purposes. The pressureswitches PS2, PS3, and PS4 report a low pressure state for diagnosticpurposes. The motor/generator 30 and motor/generator 32 will receivepressurized fluid from the main passage 54 for cooling purposes.

The electro-hydraulic control system 28 provides for controlled singlestep ratio interchanges in both an upshifting direction and adownshifting direction through engagement and disengagement ofrespective torque transmitting mechanisms when electrical power isavailable. Those skilled in the art will also recognize that theelectro-hydraulic control system 28 will permit skip shifting or doubleratio interchanges in the forward direction. A first forward range tothird forward range interchange is available by operating the trimvalves 76 and 78 to disengage the torque transmitting mechanism C1 whileengaging the torque transmitting mechanism C2. Alternately, a thirdforward range to first forward range interchange is available byoperating the trim valves 76 and 78 to engage the torque transmittingmechanism C1 while disengaging the torque transmitting mechanism C2.

Electrical Power Off Low Speed Drive Home Mode of Operation

If there is an interruption of electrical power to the electro-hydrauliccontrol system 28 and the transmission is operating with the torquetransmitting mechanism C1 engaged, the electro-hydraulic control system28 will default to an electrical power OFF, electrically variable lowspeed mode of operation. In this mode, both logic valves 144 and 156 arein the spring set position since the solenoid valves 124 and 126 arenormally closed type valves.

The trim valves 76 and 78 will move to the pressure set position sincetheir respective solenoid valves 120 and 122 are normally open typevalves. The trim valve 74 will move to the spring set position since thesolenoid valve 118 is a normally closed type valve. With the abovestated valve configuration, the torque transmitting mechanisms C2, C3,and C4 will exhaust, while the torque transmitting mechanism C1 willengage. To effect engagement of the torque transmitting mechanism C1,pressurized fluid from the main passage 54 is communicated to the outletpassage 166 of the trim valve 78. The logic valve 144 will communicatethe fluid within the outlet passage 166 to the torque transmittingmechanism C1.

The motor/generator 30 receives pressurized fluid from the main passage54 for cooling purposes. The trim valve 76 communicates pressurizedfluid from within the main passage 54 to the outlet passage 164. Thelogic valve 156 communicates the fluid within the outlet passage 164 tothe passage 170. The logic valve 144 communicates the fluid within thepassage 170 to the passage 172. The logic valve 156 communicates thefluid within the passage 172 to the passage 200, thereby increasing theflow of fluid operable to cool the motor/generator 32.

Electrical Power Off High Speed Drive Home Mode of Operation

If the electrical power to the electro-hydraulic control system 28 isinterrupted and the transmission is operating with the torquetransmitting mechanism C2 engaged, the electro-hydraulic control system28 will default to an electrical power OFF, high speed mode ofoperation. In this mode, the logic valve 156 is in a spring set positionsince the solenoid valve 126 is a normally closed type valve. The fluidpressure within the passage 140, from the normally open solenoid valve122, acting upon the differential area 152 will latch the logic valve144 in the pressure set position. This latched condition will occur whenthe logic valve 144 is in the pressure set position, i.e. the torquetransmitting mechanism C2 is engaged, and electrical power isinterrupted to the solenoid valve 124.

The trim valves 76 and 78 will move to the pressure set position sincetheir respective solenoid valves 120 and 122 are normally open typevalves. The trim valve 74 will move to the spring set position since thesolenoid valve 118 is normally closed. With the above stated valveconfiguration, the torque transmitting mechanisms C1, C3, and C4 willexhaust, while the torque transmitting mechanism C2 will engage. Toeffect engagement of the torque transmitting mechanism C2, the trimvalve 76 communicates pressurized fluid within the main passage 54 tothe outlet passage 164, which is in fluid communication with the logicvalve 144. The logic valve 144 communicates the fluid within, the outletpassage 164 to the torque transmitting mechanism C2.

The motor/generator 30 receives pressurized fluid from the passage 54for cooling purposes. The trim valve 78 communicates pressurized fluidfrom within the main passage 54 to the outlet passage 166. The logicvalve 144 communicates the fluid within the outlet passage 166 to thepassage 172. The logic valve 156 communicates the fluid within thepassage 172 to the passage 200, thereby increasing the flow of fluidoperable to cool the motor/generator 32.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A trim valve system for an electrically variable hybrid transmissioncomprising: at least one trim valve operable to selectively communicatepressurized fluid to at least one logic valve; at least one torquetransmitting mechanism in selective fluid communication with said atleast one logic valve; at least one motor/generator unit in selectivefluid communication with said at least one logic valve and operable toreceive pressurized fluid to effect cooling of said at least onemotor/generator unit; and wherein the trim valve system is characterizedby the number of said at least one trim valves being fewer than the sumof said at least one torque transmitting mechanism and said at least onemotor/generator unit.
 2. The trim valve system for an electricallyvariable hybrid transmission of claim 1, wherein said at least one logicvalve has a first position and a second position.
 3. The trim valvesystem for an electrically variable hybrid transmission of claim 2,wherein one of said at least one logic valve is operable to directpressurized fluid from one of said at least one trim valve to one ofsaid at least one torque transmitting mechanism or one of said at leastone motor/generator unit when said one of said at least one logic valveis in said first position.
 4. The trim valve system for an electricallyvariable hybrid transmission of claim 3, wherein said one of said atleast one logic valve is operable to direct pressurized fluid from saidone of said at least one trim valve to another of said at least onetorque transmitting mechanism or said one of said motor/generator unitwhen said one of said at least one logic valve is in said secondposition.
 5. The trim valve system for an electrically variable hybridtransmission of claim 1, wherein said at least one trim valve iscontrolled by a variable pressure solenoid valve.
 6. The trim valvesystem for an electrically variable hybrid transmission of claim 1,wherein said at least one trim valve is a variable pressure regulatorvalve.
 7. A trim valve system-for an electrically variable hybridtransmission comprising: a first logic valve having a first position anda second position and being operable to selectively distributepressurized fluid to a first and a second torque transmitting mechanismto selectively effect engagement of said first and said second torquetransmitting mechanisms; a second logic valve having a first positionand a second position and being operable to selectively distributepressurized fluid to a first and a second motor/generator to selectivelyeffect the cooling of said first and said second motor/generator, saidsecond logic valve being operable to selectively distribute pressurizedfluid to a third and a fourth torque transmitting mechanism toselectively effect engagement of said third and said fourth torquetransmitting mechanisms; a first trim valve operable to selectivelydistribute pressurized fluid to said second logic valve; a second trimvalve operable to selectively distribute pressurized fluid to said firstand said second logic valve; a third trim valve operable to selectivelydistribute pressurized fluid to said first logic valve; wherein saidfirst and second logic valves are in selective fluid communication withone another; wherein said first, second, and third trim valvesselectively communicate pressurized fluid to said first and second logicvalves to selectively provide engagement of said first, second, third,and fourth torque transmitting mechanisms and to selectively providecooling to said first and second motor/generators; and wherein saidfirst, second, and third trim valves and said first and second logicvalves are connected in a multiplexed arrangement such that there arefewer of said trim valves than the sum of said torque transmittingmechanisms and said motor/generators.
 8. The trim valve system for anelectrically variable hybrid transmission of claim 7, wherein said firsttrim valve is operable to selectively control the cooling of said firstmotor/generator, and said second trim valve is operable to selectivelycontrol the cooling of said second motor/generator, and said third trimvalve is operable to control the engagement of said first torquetransmitting mechanism when said first and second logic valves are insaid first position.
 9. The trim valve system for an electricallyvariable hybrid transmission of claim 7, wherein said first trim valveis operable to selectively control the cooling of said firstmotor/generator, and said second trim valve is operable to selectivelycontrol the engagement of said second torque transmitting mechanism, andsaid third trim valve is operable to control the cooling of said secondmotor/generator when said first logic valve is in said second positionand said second logic valve is in said first position.
 10. The trimvalve system for an electrically variable hybrid transmission of claim7, wherein said first trim valve is operable to selectively control theengagement of said fourth torque transmitting mechanism, and said secondtrim valve is operable to selectively control the engagement of saidsecond torque transmitting mechanism, and said third trim valve isoperable to control the engagement of said first torque transmittingmechanism when said first logic valve is in said first position and saidsecond logic valve is in said second position.
 11. The trim valve systemfor an electrically variable hybrid transmission of claim 7, whereinsaid first trim valve is operable to selectively control the engagementof said fourth torque transmitting mechanism, and said second trim valveis operable to selectively control the engagement of said second torquetransmitting mechanism, and said third trim valve is operable to controlthe engagement of said third torque transmitting mechanism when saidfirst logic valve is in said second position and said second logic valveis in said second position.
 12. The trim valve system for anelectrically variable hybrid transmission of claim 7, wherein saidfirst, second, and third trim valves are controlled by a variablepressure solenoid valve.
 13. The trim valve system for an electricallyvariable hybrid transmission of claim 7, wherein said first, second, andthird trim valves are variable pressure regulator valves.
 14. The trimvalve system for an electrically variable hybrid transmission of claim7, wherein said first and second logic valves are multiplex valves. 15.A trim valve system for an electrically variable hybrid transmissioncomprising: a first logic valve having a first position and a secondposition and being operable to selectively distribute pressurized fluidto a first and a second torque transmitting mechanism to selectivelyeffect engagement of said first and second torque transmittingmechanisms; a second logic valve having a first position and a secondposition and being operable to selectively distribute pressurized fluidto a first and a second motor/generator to selectively effect thecooling of said first and second motor/generator, said second logicvalve being operable to selectively distribute pressurized fluid to athird and a fourth torque transmitting mechanism to selectively effectengagement of said third and fourth torque transmitting mechanisms; afirst trim valve operable to selectively distribute pressurized fluid tosaid second logic valve; a second trim valve operable to selectivelydistribute pressurized fluid to said first and second logic valve; athird trim valve operable to selectively distribute pressurized fluid tosaid first logic valve; wherein said first and second logic valves arein selective fluid communication with one another; wherein said firsttrim valve is operable to selectively control the cooling of said firstmotor/generator, and said second trim valve is operable to selectivelycontrol the cooling of said second motor/generator, and said third trimvalve is operable to control the engagement of said first torquetransmitting mechanism when said first and second logic valves are insaid first position; wherein said first trim valve is operable toselectively control the cooling of said first motor/generator, and saidsecond trim valve is operable to selectively control the engagement ofsaid second torque transmitting mechanism, and said third trim valve isoperable to control the cooling of said second motor/generator when saidfirst logic valve is in said second position and said second logic valveis in said first position; wherein said first trim valve is operable toselectively control the engagement of said fourth torque transmittingmechanism, and said second trim valve is operable to selectively controlthe engagement of said second torque transmitting mechanism, and saidthird trim valve is operable to control the engagement of said firsttorque transmitting mechanism when said first logic valve is in saidfirst position and said second logic valve is in said second position;wherein said first trim valve is operable to selectively control theengagement of said fourth torque transmitting mechanism, and said secondtrim valve is operable to selectively control the engagement of saidsecond torque transmitting mechanism, and said third trim valve isoperable to control the engagement of said third torque transmittingmechanism when said first logic valve is in said second position andsaid second logic valve is in said second position; and wherein saidfirst, second, and third trim valves and said first and second logicvalves are connected in a multiplexed arrangement such that there arefewer of said trim valves than the sum of said torque transmittingmechanisms and said motor/generators.
 16. The trim valve system for anelectrically variable hybrid transmission of claim 15, wherein saidfirst, second, and third trim valves are controlled by a variablepressure solenoid valve.
 17. The trim valve system for an electricallyvariable hybrid transmission of claim 15, wherein said first, second,and third trim valves are variable pressure regulator valves.
 18. Thetrim valve system for an electrically variable hybrid transmission ofclaim 15, wherein said first and second logic valves are multiplexvalves.